stage2: building musl: fix typo in replacing path separators
stage2: building musl: fix typo in replacing path separators

raulgrell/zig,raulgrell/zig,andrewrk/zig,raulgrell/zig,raulgrell/zig,zig-lang/zig,andrewrk/zig,raulgrell/zig,zig-lang/zig,zig-lang/zig